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      <title>延迟消息的设置方法 - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>延迟消息的设置方法 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
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        const quizData = [
  {
    "question": "在RocketMQ中，当生产者发送一个延迟消息时，Broker会如何处理这条消息？",
    "options": [
      "Broker会拒绝该消息，因为默认不支持延迟。",
      "Broker将消息直接投递给消费者，并附带一个延迟处理的指令。",
      "Broker会将消息的Topic修改为内部专用的SCHEDULE_TOPIC_XXXX，并将原始Topic信息存入消息属性中，等待后续投递。",
      "Broker会一直保持与生产者的连接，直到延迟时间到达后再完成消息的接收。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "RocketMQ延迟消息的实现原理是，Broker在接收到延迟消息后，并不会立即将其投递到业务原始的Topic。相反，它会修改消息的目标Topic为一个内部专用的延迟主题（SCHEDULE_TOPIC_XXXX），同时将原始的Topic和队列ID等信息作为属性保存起来。然后，一个定时服务会扫描这个内部主题，当消息到达预定的投递时间时，再将消息恢复其原始Topic并进行投递。",
    "source": "文档中「延迟消息的实现原理」-「详细实现流程」部分",
    "hint": "文档中提到，Broker会识别延迟消息并“修改消息的Topic为内部主题SCHEDULE_TOPIC_XXXX”。"
  },
  {
    "question": "根据文档中提供的RocketMQ默认延迟等级，如果开发者想让一条消息延迟30分钟后再被消费，应该将消息的`delayTimeLevel`设置为多少？",
    "options": [
      "15",
      "16",
      "17",
      "18"
    ],
    "correctAnswerIndex": 1,
    "explanation": "根据文档中列出的默认18个延迟等级表，等级16对应的延迟时间是30分钟（30m）。因此，要实现30分钟的延迟，需要将`delayTimeLevel`设置为16。",
    "source": "文档中「设置延迟等级的方法和参数」-「RocketMQ的延迟等级机制」部分",
    "hint": "请查阅文档中关于默认18个延迟等级的具体时间对应关系列表。"
  },
  {
    "question": "以下哪个场景最不适合使用RocketMQ的延迟消息功能？",
    "options": [
      "电商系统中，用户下单后30分钟内未支付，系统自动取消该订单。",
      "在视频转码服务中，需要确保后一个转码任务在前一个任务完成后立即开始。",
      "在预约挂号系统中，需要在就诊前一天通过短信提醒用户。",
      "在一个限时秒杀活动中，优惠券在发放2小时后自动失效。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "RocketMQ的延迟消息不支持严格的顺序消息。视频转码任务通常要求严格的先后顺序，前一个任务的完成是后一个任务开始的触发条件，这属于顺序消息的范畴。而订单超时关闭、预约提醒、优惠券失效等场景都是典型的基于时间的触发机制，非常适合使用延迟消息。",
    "source": "文档中「延迟消息的使用限制与最佳实践」-「使用限制」-「顺序消息限制」部分",
    "hint": "考虑一下延迟消息的哪个“使用限制”会影响到这个场景的实现。"
  },
  {
    "question": "如果RocketMQ默认的延迟等级无法满足特定的业务需求（例如需要一个2.5小时的延迟），应该如何操作？",
    "options": [
      "无法实现，只能在业务代码中通过`Thread.sleep()`来等待。",
      "在发送消息时动态指定任意的延迟毫秒数。",
      "修改Broker的配置文件（broker.conf），在`messageDelayLevel`属性中增加或修改延迟等级配置。",
      "向RocketMQ社区提交请求，等待下一个版本支持该功能。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "当默认的延迟等级不满足需求时，RocketMQ允许用户通过修改Broker的配置文件（例如`broker.conf`）中的`messageDelayLevel`参数来自定义一套新的延迟等级。修改后重启Broker即可生效。",
    "source": "文档中「设置延迟等级的方法和参数」-「自定义延迟等级」部分",
    "hint": "文档中提到了一个修改Broker配置文件来自定义延迟等级的方法。"
  },
  {
    "question": "在RocketMQ延迟消息的实现架构中，哪个组件负责检查存储在延迟队列中的消息是否到期，并将其投递到原始Topic？",
    "options": [
      "Producer端的定时器",
      "Consumer端的拉取调度器",
      "Broker中的ScheduleMessageService",
      "NameServer中的路由服务"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Broker内部的`ScheduleMessageService`是实现延迟消息的核心组件之一。它是一个定时检查服务，会周期性地扫描内部的延迟队列（SCHEDULE_TOPIC_XXXX），判断其中的消息是否到达了预设的投递时间。一旦发现到期消息，它就会负责将该消息重新构建并投递到其原始的业务Topic中。",
    "source": "文档中「延迟消息的实现原理」-「整体架构」和「定时检查阶段」部分",
    "hint": "文档中描述实现原理时，提到了一个专门的“定时检查服务”。"
  },
  {
    "question": "关于RocketMQ延迟消息的使用限制，以下哪项描述是正确的？",
    "options": [
      "延迟消息的精度可以达到毫秒级别。",
      "延迟消息会保证先进先出（FIFO）的严格顺序。",
      "RocketMQ只支持预设的延迟等级，不支持任意时间点的精确设置。",
      "发送延迟消息不会消耗额外的系统资源。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "RocketMQ延迟消息的一个主要限制是其延迟精度有限。它不支持用户设置任意的、精确到秒或毫秒的延迟时间，而是通过预设的固定“延迟等级”来实现。用户只能选择其中一个等级，系统会按照该等级对应的时间进行延迟投递，这可能导致秒级的误差。",
    "source": "文档中「延迟消息的使用限制与最佳实践」-「使用限制」-「延迟精度有限」部分",
    "hint": "思考一下RocketMQ延迟消息在“时间设置”上有什么特点或限制。"
  },
  {
    "question": "在延迟消息被重新投递到原始Topic供消费者消费时，消费端程序的感知是怎样的？",
    "options": [
      "消费者能感知到这是一条延迟消息，并能获取到原始的延迟等级。",
      "消费者完全无感知，它收到的消息和一条普通的即时消息没有区别。",
      "消费者需要使用特殊的API来订阅和消费延迟消息。",
      "消费者会先收到一个通知消息，然后再收到真正的业务消息。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "整个延迟过程对消费者是透明的。当延迟时间到达，Broker将消息从内部的SCHEDULE_TOPIC_XXXX恢复并投递到原始业务Topic后，对于订阅了这个业务Topic的消费者来说，它接收到的就是一条普通的消息。消费者无需特殊处理，也无法直接感知到这条消息曾经被延迟过。",
    "source": "文档中「延迟消息的实现原理」-「消息投递阶段」部分",
    "hint": "文档中提到“消费者从原始Topic消费消息，对延迟过程无感知”。"
  }
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                '<div class="score-card">' +
                '<h3>错误率</h3>' +
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                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  